Abstract: Objective To find the novel treatment target of agravity-induced adverse reactions by studying the effect of simulated agravity on the barrier function of pulmonary micro-vascular endothelial cells(PMVEC). Methods Effect of agravity on PMVECs was simulated with a clinostat.PMVEC were gyratorily cultured for 72h and 1g of PMVEC was statically cultured as controls.Cytoskeletal F-actin was marked with immunofluorescence staining and changes of cytoskeleton were observed under laser confocal microscope.Adhesion of monocytes(THP-1) to PMVEC was observed under light microscope and their adhesion rate was calculated.Green fluorescence-labeled adenovirus-infected PMVEC were observed under fluorescence microscope and detected by flow cytometry. Results After 72h of gyratory culture,the expression level of F-actin in PMVEC was lower,the drawing and direction feelings of microfilament were significantly weaker,the arrangement of PMVEC was looser and their extension was poorer,and the volume of PMVEC was smaller.Stimulated agravity suppressed the adhesion of PMVEC to THP-1,leading to their adhesion rate decreased from 51.25%±8.2% to 37.69%±6.5%(P<0.05) and the adenovirus infection rate of PMVEC increased from 66.32%±5.74% to 84.55%±5.31%(P<0.05). Conclusion Simulated agravity can injure the barrier function of PMVEC.